Urinary incontinence among female soldiers
Urinary incontinence has traditionally been regarded as a problem primarily affecting older multiparous women. The correlation between urinary incontinence and both parity and age has been well established. Although most women and many health care professionals consider absolute continence under all circumstances as “normal,” evidence suggests that urinary incontinence during stressful physical activity is common among young, physically active women, even in the absence of known risk factors for incontinence. 1-3 Nygaard3 found that 28% of nulliparous athletes reported urine loss while participating in their sport. She also noted that 20% of incontinent exercisers discontinued the exercise as a result of the incontinence. Bo4 studied healthy, fit, nulliparous women in Norway and reported that one-fifth of them had social or hygienic problems resulting from stress urinary incontinence. The psychosocial effect of urinary incontinence can be more devastating than the health consequences, with multiple and broad-reaching effects that influence daily activities, social interactions, and self-perceptions of health status.56 Rosenzweig7 reported increased sleep disturbance, increased tension, and worsening depression in women with urinary incontinence. The perception of the severity of incontinence is unique to each individual, and the perceived effect of incontinence and objective measures of its severity are not directly proportional.8
Urinary incontinence poses challenges to the female soldier unparalleled in her civilian counterparts. Active duty soldiers must maintain peak physical condition and remain in a constant state of readiness. Female soldiers are assuming more physically demanding roles and have limited ability to discontinue exercises or change the way specific exercises are performed. Duty requirements often subject the soldier to marked and sudden increases in intra-abdominal pressure, which likewise are difficult for the soldier to modify. Urinary incontinence can be particularly debilitating during field exercises. Field conditions often provide limited access to hygienic measures commonly used by the incontinent patient. In cold-weather exercises, incontinence may pose major risks to the soldier’s health and effectiveness.
Although the pathogenesis of urinary incontinence and pelvic organ prolapse is doubtless complex, lifestyle has long been implicated. Nichols and Randall9 noted, “often nulliparous prolapse will be associated with a lifestyle of heavy physical labor that involves recurring marked increases in intra-abdominal pressure.”
Because the lifestyle of the female soldier could conceivably predispose her to the development of urinary incontinence, and the conditions in which the soldier must function make adaptive measures difficult, this study was undertaken. We conducted a descriptive questionnaire study to examine the prevalence of the symptom of urinary incontinence in active duty female soldiers during the performance of their duties and while participating in physical training and field exercises. We also evaluated and compared the prevalence of incontinence during activities of daily life and recreational exercise. The soldiers were asked to list the adaptive measures they used to continue exercise and perform their duties. Subjects
Seven hundred thirteen female soldiers from several units at Fort Lewis, Washington, Fort Benning, Georgia, and Fitzsimons Army Medical Center, Colorado, were asked to complete a selfadministered questionnaire to evaluate the prevalence of the symptom of urinary incontinence while performing their duties and during physical training or field exercises, as well as while participating in the activities of daily life and recreational exercise. Five hundred sixty-three female soldiers in these units completed the questionnaire, for a response rate of 79%.
The self-administered questionnaire addressed basic demographic information, including height, age, parity, weight, and race, as well as exercises in which the subjects participated. The questionnaire also included the subjects’ present and past job descriptions or military occupational specialties.
Urinary incontinence was assessed by the question, “Have you ever leaked urine? By leaking urine we mean involuntary loss beyond your control to the extent that it becomes a social or hygienic problem.” In addition, the subjects rated the frequency as follows: (a) less than 25% of the time; (b) 25-50% of the time; or (c) more than 50% of the time.
Soldiers were questioned whether they had experienced incontinence during the following activities of daily life: (a) coughing or sneezing; (b) lifting; (c) vacuuming; (d) raking or hoeing; (e) lawn mowing; (f moving furniture; or (g) walking to the bathroom and hearing the sound of running water. They rated the frequency as: (a) less than 25% of the time; (b) 25-50% of the time; or (c) more than 50% of the time.
They were also questioned about incontinence with recreational sports, including weight lifting and high-impact aerobics (those aerobic exercises in which both feet leave the floor during jumps). Soldiers were asked to describe their jobs or duties and explain how urinary problems affected their regular duties. They were also asked to list any precautions they commonly used to prevent urine loss during physical training or duty. They were specifically asked if they restricted fluids to prevent urine loss.
All female active duty soldiers in each participating unit were asked to complete the questionnaire as they assembled for physical testing. All data were analyzed using frequency distributions and independent group t tests. Results
The general demographic features of the 563 soldiers who completed the questionnaires were analyzed. The mean age of the group was 28.3 years, with a range of 18 to 51 years. Thirty percent of the soldiers who answered the questionnaire stated that they leaked urine during some activity to the extent that they considered it to be a social or hygienic problem. The mean weight of the subjects was 134.7 pounds, with a mean height of 65.1 inches. All subjects met the height and weight parameters required for active duty soldiers. Seventy-six percent had regular menses, and 28% were taking oral contraceptives at the time they completed the questionnaire. The racial distribution of the group was similar to the makeup of the Army as a whole, with 75% white, 18% black, 2% Asian, and other races constituting the remaining 5%. The mean number of years the subjects reported problematic urinary incontinence was 5.1 years, and ranged from less than 1 year to more than 20 years.
The mean age of the soldiers reporting activity-induced symptomatic urinary incontinence (32.2 years) was significantly greater (p
There were no significant differences in height between the continent and the incontinent group, but those soldiers reporting urinary incontinence with activity were significantly heavier (mean weight of 137.7 pounds) than the continent soldiers (mean of 127.5 pounds) (p
Although more than 30% of the soldiers questioned reported symptomatic urine loss with activity, the frequency varied greatly with the activity performed. The soldiers’ perception of the severity of the incontinence also appeared to be related to the activity performed. Relationships between urinary incontinence and activity are illustrated in Figure 3.
Thirty-three percent of the soldiers reported urinary urgency during physical training, 30% noticed urinary frequency after physical training, and 9% reported bladder pain during or after physical training. The soldiers were asked how often urinary incontinence posed a social or hygienic problem, and with which activities. The responses are illustrated in Figure 4.
Of those soldiers reporting symptomatic urinary incontinence during the performance of duties, considerable differences were noted among the various job descriptions or military occupational specialties. The differences among specialties are illustrated in Figure 5.
Although 31% of the incontinent soldiers stated that they would modify physical training, field duties, or their military occupational specialties to prevent urinary incontinence, fewer than 8% discontinued exercise or changed their military occupations because of urinary incontinence.
The questionnaire also addressed whether or not soldiers used precautions or adaptive measures such as fluid restriction or barrier methods such as tampons to decrease urinary incontinence during activity. We also questioned the type of measures the soldiers commonly used. Overall, 68% of the soldiers questioned stated that they commonly took measures such as emptying their bladders or wearing pads as a precaution against incontinence before strenuous activity.
Fifteen percent of the soldiers used more than one preventive measure, such as both pads and fluid restriction. Nineteen percent of the soldiers interviewed restricted fluids before their physical training tests, and 13% restricted fluids during field exercises to reduce both incontinent episodes and the need to urinate. Figure 6 illustrates those activities for which female soldiers commonly take precautions to avoid incontinence.
Activities included as daily activities in the questionnaire were coughing, sneezing, lifting, vacuuming, raking, lawn mowing, and moving furniture. The prevalence of urinary incontinence (occurring more than 25% of the time) with these activities were: coughing, 6%; lifting, 3%; moving furniture, 2%; vacuuming, 1%; raking, 1%; and lawn mowing, 2% (with a total reported incidence of incontinence of 16% for daily activities). Less than 1% of the subjects reported incontinence while walking to the bathroom or hearing the sound of running water.
Twenty-four percent of the respondents reported urinary loss occurring more than 25% of the time during recreational exercise. Recreational exercises in which the subjects participated more than twice a week included aerobic exercise (42%), running (35%), weight lifting (18%), walking (21%), swimming (5%), golf (3%), tennis (8%), and bicycling (8%). The highest frequency of urinary incontinence was reported during tennis and running. Although 30% of the soldiers reported incontinence during the 2-mile run at physical testing, fewer than 12% reported urinary incontinence with recreational running. Eighteen percent of those subjects participating in tennis reported urinary incontinence more than 25% of the time. The lowest incidence of incontinence was reported by golfers (0%) and swimmers (4%).
Eleven subjects (1.9%) reported previously undergoing hysterectomy, and four subjects (0.7%) reported previously undergoing surgical correction of urinary incontinence. In addition to urinary incontinence, 7.8% of the female soldiers questioned reported uncontrollable loss of stool or gas during strenuous activity as a social and hygienic problem. Eighty-six percent of those reporting this problem were parous. Overall, 19% of the respondents stated that they regularly practiced Kegel’s exercises.
It is clear from this study that the symptom of urinary incontinence poses a pervasive problem for the active duty female soldier. It must be emphasized that this study was designed to evaluate the symptom of urinary incontinence rather than the condition of urinary incontinence. The symptom of urinary incontinence, for the purposes of this study, is defined as the loss of urine beyond the subject’s control to the extent that it is perceived to be a social or hygienic problem. The condition of urinary incontinence, as defined by the International Continence Society, is Involuntary loss of urine which is objectively demonstrable and a social or hygienic problem.”lo The symptom of urinary incontinence is reported to be more common than the condition of urinary incontinence.lo
Sherman et al.ll studied active duty female soldiers with the symptom of urinary incontinence and found that on urodynamic evaluation 77% had stress urinary incontinence, 23% had mixed incontinence, and no subject demonstrated pure urge incontinence. This study does not attempt to differentiate the symptoms of stress or urge incontinence, because our primary interest was the prevalence of urinary incontinence and its effect on the soldier’s health and performance.
The prevalence of urinary incontinence in this young group of women who are in peak physical condition is consistent with that reported by other researchers. Nemar and Middleton 2 found that more than half of nulliparous nursing students had noticed incontinence at least once during coughing, laughing, or excitement. Bo and Machlum’3 compared the prevalence of incontinence between sedentary college students and physically active students who trained more than three times per week; they found that physically active students were more likely to report urinary incontinence, particularly during jumping and running. Nygaard3 found that 67% of female gymnasts reported urine loss only during gymnastics and never during activities of daily life.
Although age and parity are widely recognized as major contributors to the development of urinary incontinence, factors involved in the transient failure of an active young women’s continence mechanisms are far less clear. A better understanding of these factors could lead to modifications resulting in prevention or abatement of urinary incontinence in these individuals
In recent years, much research has been done regarding the pelvic floor and its relationship to incontinence, including studies on the connective tissue,14 the striated muscle,ls and the innervation of both striated and smooth muscle. 16 Factors may also include inadequate abdominal pressure transmission and pelvic-floor muscle fatigue. Ulmston and Ekmanl7 found that nulliparous women with urinary incontinence had less tissue collagen concentration compared with continent controls. The relationship between genital prolapse and connective tissue was further studied by Norton, Is who reported that women with joint hypermobility had a significantly higher prevalence of genital prolapse compared with women with normal mobility. However, she found no differences in the prevalence of stress urinary incontinence between the two groups.
Pelvic-floor muscle fatigue has been implicated particularly with reference to incontinence during prolonged or intense physical exertion. Enhorning”9 reported that continent subjects recorded an increase in urethral pressure 0.1 to 0.3 seconds before a cough and the resultant increase in intra-abdominal pressure. He observed that this antecedent increase in urethral pressure was absent in incontinent subjects and reasoned that this phenomenon was probably attributable at least in part to an interaction between the levator ani, the compressor urethrae, and the urethrovaginal sphincter muscles. The compressor urethrae and the urethrovaginal sphincters are composed of a larger percentage of fast-twitch muscles than the levator ani and exert their influence primarily on the distal 20% of the functional urethra. It is plausible that the levator ani are more responsible for the long-term support of the urethra. Although the exact mechanism of their response is doubtless complex, Nygaard3 reasoned that the levator ani muscles, which consist of both slow-twitch and fast-twitch fibers, may be responsible for this active component of continence: “The pelvic floor must be able to respond forcefully and rapidly to withstand the constant repetitive deceleration of the abdominal viscera on the pelvic floor caused by repetitive jumping or running.” She speculated that transitory incontinence among athletes may be at least partially caused by generalized muscle fatigue, including pelvic-floor muscle fatigue. The prevalence of transitory urinary incontinence during prolonged physical training or field marches found in this study tends to support this hypothesis.
The levator ani muscles have a higher proportion of slowtwitch fibers (66%) than are found in other female human muscles (48%).2o Lash21 found that the capacity of skeletal muscle to perform prolonged work of moderate intensity is dependent on its aerobic capacity. The aerobic capacity of all muscle fiber types increases with endurance training, with the greatest increases observed in slow-twitch fibers (type I) after continuous training and in fast-twitch fibers (type IIa) after interval training. Most pelvic-floor exercises used by female soldiers are of the interval-training variety. This raises the question of whether pelvic-floor exercises geared toward endurance training would more effectively prepare the soldier for the prolonged work required of the pelvic floor during long periods of stress such as during physical training or road marches. In addition, the process of marching with field packs places considerable weight on the back, shoulders, and hip girdle. This, in turn, results in increased transfer of force to the heel of the foot.
Hay22 found that long-jumpers who land on their heels can generate ground-reaction forces up to 16 times their body weight. This is in contrast to the lower forces of 3 times the body weight seen with the toe-heel landings recorded after a front handspring. Preliminary studies suggest that rigid soled footwear, similar to the typical “combat boots or jump boots” worn by the majority of soldiers, may actually increase the transfer of force from the heel back to the pelvic floor. Nygaard3 raised the question of “whether protective footwear may play some role in preventing incontinence and/or prolapse.”
The long-term effect of prolonged stressful activity on the pelvic floor has not been completely determined. Davis and Goodman23 reported on six nulliparous female infantry trainees who developed pelvic-floor support defects and stress incontinence during the course of airborne training. However, these subjects appeared to have developed endopelvic fascial tears precipitated by isolated traumatic events.
Nygaard, in an unpublished retrospective cohort study of female Olympians, found that even though high-impact athletes were more likely to report urinary incontinence when they were performing their sport than low-impact athletes (35.8 vs. 4.5%) they did not have a significantly greater risk of developing urinary incontinence 20 to 30 years later compared with lowimpact athletes.
The finding that incontinent soldiers were significantly heavier than their continent counterparts, in spite of there being no significant difference in their height, is consistent with previous unpublished studies by Nygaard. The association between body mass index and clinically significant incontinence appeared to be more marked than that of parity and incontinence. At present, there are no data regarding whether urinary incontinence improves after weight loss in women who are moderately obese.
Physical training was clearly the activity that most commonly precipitated urinary incontinence (31%) in female soldiers and that most consistently produced the incontinence (26% reported that incontinence occurred more than 50% of the time). This activity was also more likely than any other activity to produce incontinence that was perceived to be of social or hygienic significance by the soldier. The intensity of preparation for the Army Physical Training Test is likely to be a factor in this perception. The soldier must perform a series of sit-ups and pushups and then run 2 miles within stringent time requirements. Because these exercises are performed in groups, any degree of incontinence can easily be perceived of as social or hygienic significance.
Field exercises, which routinely entail forced marches with heavy field packs, also precipitated incontinence in a large percentage (26%) of the soldiers questioned. In field conditions, the incontinent soldier often finds limited access to the hygienic measures commonly used by her civilian counterparts. In addition, cold weather or chemical warfare protective clothing make voiding difficult and cumbersome. Not surprisingly, 24% of the soldiers found urinary incontinence to pose social or hygienic problems during field duty.
During daily activities and recreational exercises, the soldier is more in control of her continence. Toilet facilities are readily available, and the soldier can discontinue the activity when urge or incontinence occurs. Even though 16% of the soldiers reported incontinence during daily activities and 24% had incontinence during recreational exercises, only 6 and 8%, respectively, considered it to be a social or hygienic factor, and most considered it a problem less than 50% of the time.
One interesting finding was that the military occupational specialty with the highest incidence of job-related urinary incontinence was that of petroleum technician. These soldiers drive fuel trucks, often over rough terrain, and then jump from the cab at a run to rapidly refuel military vehicles in the field. The exact mechanism of this incontinence is currently being investigated with ambulatory urodynamic recordings; however, we believe that the rapidly changing forces involved in moving from a sitting position to the shock of jumping down and running may be enough to overcome the contractility of a relatively relaxed pelvic floor.
Also of interest is that there appears to be a higher incidence of urinary incontinence in military occupational specialties that require heavy lifting but do not place an emphasis on daily group exercises, as is done in units more closely associated with combat units. This may be a factor in the relatively high incidence of urinary incontinence reported by cooks and supply personnel compared with female soldiers in the military police and Special Forces, whose units place more emphasis on group exercise.
Sixty-eight percent of the subjects stated that they used adaptive measures as a precaution against urinary incontinence during physical training. The most commonly used mechanism was frequent urination or urination just before intense physical activity such as physical training. The soldiers frequently (11%) used mechanical devices such as tampons or, rarely, pessaries. And even though both devices have proven to be useful in alleviating incontinence, their use in the field is cumbersome and their efficiency in field conditions have not been studied. Recent developments and newer, more efficient (even disposable) mechanical devices may make this option more attractive to the active duty soldier for the prevention of urinary incontinence in field conditions.
This study suggests that urinary incontinence during strenuous activity is common among female soldiers. The mechanism is doubtless complex. As Nygaard3 concluded: “It seems logical that a woman’s continence depends not only on her actual anatomical, hormonal, cellular, and neurologic composition, but also, and perhaps more importantly, on the stresses to which the pelvic floor is exposed. This balance is represented by the concept of a continence threshold which, when exceeded, results in urine loss, even in women with no conventional risk factors for incontinence.”
Although the concept that the normal woman should be continent under all circumstances appears unreasonable, a better understanding of the factors promoting continence, particularly during strenuous exercise, is vital for those caring for the active woman and the female soldier in particular.
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Guarantor: COL Gary Davis, MC USA
Contributors: COL Gary Davis, MC USA*; LTC Richard Sherman, MS USAt; Melissa F. Wong, BAt; LTC George McClure, MC USA*; COL Romeo Perez, USA*; COL Milo Hibbert, USA*
*Department of Obstetrics and Gynecology, and +Department of Clinical Investigations, Madigan Army Medical Center, Tacoma, WA 98431.
Copyright Association of Military Surgeons of the U.S. Mar 1999
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